1. Field
Example embodiments relate to methods of fabricating image sensors and image sensors fabricated by the methods. Also, example embodiments relate to methods of fabricating image sensors and image sensors fabricated by the methods in which the number of masks required to fabricate the image sensors may be decreased.
2. Description of Related Art
Typically, an image sensor functions to convert an optical image to an electrical signal. With the recent developments in computer industries and communication industries, the demand for image sensors having improved performance is increasing in various fields, including those of digital cameras, camcorders, PCS (Personal Communication Systems), game kits, guard cameras, medical micro cameras, robots, etc.
In particular, a metal-oxide semiconductor (MOS) image sensor having a simple driving process may be realized through various scanning manners. Further, since a signal processing circuit is integrated in a single chip, the size of a product may be decreased and the cost of fabricating such a sensor may be reduced due to the compatible MOS process technology. Furthermore, the MOS image sensor has very low power consumption, and therefore can be applied to a product having a limited battery capacity. Accordingly, the use of the MOS image sensor is drastically increasing, owing to the technological development thereof and the ability to realize high resolution.
In such an MOS image sensor, a light-receiving element is exemplified by a pinned photodiode (PPD) including an n-type dopant region formed in the substrate and a p-type dopant region formed on the surface of the substrate. Here, the n-type dopant region functions as a potential well for accumulating a charge corresponding to the amount of incident light to be absorbed, while the p-type dopant region functions as a potential barrier preventing the flow of the charge, generated by defects on the surface of the substrate, into the n-type dopant region.
However, according to a conventional image sensor fabrication method, since an additional mask is required to form the p-type dopant region, it is necessary to perform a plurality of additional processes including the application of a photoresist film, photolithography, and removal of the photoresist film.